Keyboard operated transmitter

ABSTRACT

A keyboard operated telegraph transmitter having an array of keys is provided. The transmitter includes a plurality of code bars which are shiftable by the depression of the keys and also includes switching means operatively connected to and actuated by the shifting of the code bars. The switching means includes a circuit board having a plurality of conductive areas positioned on a surface thereof, and a contact means which is secured to each of the code bars and electrically connects several of the conductive areas on the circuit board. When the code bars are shifted the movement is transformed into an output coded signal from the circuit board. Additional features of the transmitter include a parity check system, and a motion multiplying mechanism which is designed to facilitate the operation of the keyboard. Still another feature is the inclusion of three shift keys for the purpose of transmitting a maximum number of indicia with a minimum number of keys.

' United States Patent Donovan et al.

[451 Mar. 21, 1972 [54] KEYBOARD OPERATED TRANSMITTER [72] lnventors: Timothy F. Donovan, Huntington; William P. Ryan, Bethany, both of Conn.

[73] Assignee: Mite Corporation, New Haven, Conn.

[22] Filed: Sept. 4, 1969 [211 App]. No.: 855,260

[52] US. Cl. ..178/17 C [51] Int. Cl. ..H04l 17/12 [58] FieldofSearch.... "178/17C, l7A,17 B, 17E, 178/17 D, 79, 80, 81

[5 6] References Cited UNITED STATES PATENTS 3,494,550 2/1970 Hayes et al. ..200/5 E 2,964,986 12/1960 Johnson ...200/5 A 3,120,656 2/1964 Waller et al. ..340/347 3,306,417 2/1967 Gassino et al ..l97/l7 Primary Examinerl(athleen H. Claffy Assistant Examiner-Horst F. Brauner AnorneyJames and Franklin [57] ABSTRACT A keyboard operated telegraph transmitter having an array of keys is provided. The transmitter includes a plurality of code bars which are shiftable by the depression of the keys and also includes switching means operatively connected to and actuated by the shifting of the code bars. The switching means includes a circuit board having a plurality of conductive areas positioned on a surface thereof, and a contact means which is secured to each of the code bars and electrically connects several of the conductive areas on the circuit board. When the code bars are shifted the movement is transformed into an output coded signal from the circuit board. Additional features of the transmitter include a parity check system, and a motion multiplying mechanism which is designed to facilitate the operation of the keyboard. Still another feature is the inclusion of three shift keys for the purpose of transmitting a maximum number of indicia with a minimum number of keys.

15 Claims, 7 Drawing Figures PATENTEDMARZ] I972 SHEET 1 [IF 3 INVENTOR$ TIMOTHY E DONOVAN WILLIAM R RYAN r O I HERE I I II II II II UUUUUUU N l NN monuevs PATE-NTEDMAR 21 I972 SHEET 2 BF 3 INVFNTORS TlMOTHY E DONOVAN ATTORNEYS WILLIAMP. RYAN 9 4 M PATENTEUMARZI E972 SHEET 3 0F 3 4 A 8 0: Q5 o:

g INVI.L'NT(I)RS TIMOTHY F. DONOVAN WILLIAM P. RYAN W MM V QQ 0 M: a VI... mm

x v: cow 0: h ww 0.: 5% z 5 2. 5 0.5 0

ATTORNEYS am M mm mm KEYBOARD OPERATED TRANSMITTER This invention relates to transmitters, and more particularly to a keyboard operated telegraph transmitter.

A keyboard operated telegraph transmitter has a keyboard comprising an array of keys which are pressed by the operator and which set up a coded signal in response to the depression of the keys. The coded signal, which is different for each key, is transmitted to a receiver which decodes and prints the message. The coded signal may be forwarded in a serialized transmission on a telegraph line or may be arranged for parallel transmission on a number of lines.

The transmitter usually includes switching devices which function to properly vary the signal each time a different key is depressed. When parallel transmission is employed, the switching devices must be arranged to cooperate with the depressed keys to provide a multilevel signal which is coded to correspond to the particular key. Each key requires a different coded signal for each symbol or indicia placed thereon and thus a large number of such coded signals are required for a typical keyboard transmitter. It is important therefore that the switching devices be capable of providing these output signals quickly and accurately without requiring an inordinate amount of space within the transmitter and thus without the use of a large number of complex mechanical switches.

Another important consideration in a keyboard operated transmitter is the number of characters or symbols which can be transmitted. For obvious reasons it is highly desirable to include as few keys as possible on the keyboard. It is also most desirable to have a transmitter which is capable of transmitting as many indicia as possible. One solution to this dilemma is to provide several indicia on each key. However, such a solution invites further difficulty since several coded signals must be separately generated for a single key. While this may be done with some measure of success without unnecessarily burdening the operator and slowing down the transmission, there is currently a limit to the number of indicia which may be transmitted with a standard size keyboard.

It is therefor the primary object of this invention to provide a telegraph transmitter which overcomes the foregoing difficulties. It is another more specific object of this invention to provide a keyboard transmitter which includes an improved switching means to enable the output signal to be transmitted quickly, reliably and accurately. It is still another object of this invention to provide a keyboard operated transmitter which permits a large number of indicia to be transmitted with a minimum number of keys and with a minimum of operational difficulty.

Broadly, the invention comprises a keyboard operated transmitter which includes a plurality of keys, a group of code bars which are shiftable by the depression of the keys, and switching means operatively connected to and actuated by the code bars upon the shifting thereof. The code bars are generally positioned substantially parallel to each other and perpendicular to the keys. in the preferred embodiment, the switching means comprises a circuit board having a plurality of conductive areas, and a contact means which is secured to each of the code bars and operatively connected to the circuit board. The contact means has a part which is integrally connected to a code bar and also includes an electrically conductive member which contacts the circuit board. When the code bar is shifted, the conductive member is also shifted along the circuit board to thereby connect specific conductive areas on the board. Some of the conductive areas are connected to a voltage power supply while others are not. Thus in one code bar position the output signal from these conductive areas includes a voltage which in the normal terminology applied is referred to as a l or a bit. When the code bar is repositioned, the conductive member is also repositioned thereby connecting other areas on the circuit board which are not connected to the voltage supply so as to provide an output signal with no voltage, and this is normally referred'to as The output signal from the circuit board will therefore either include or not include a voltage depending upon the several positions of a code bar. If a large number of code bars are shifted by the depression of a single key, a parallel output signal with as many ls or Os as there are code bars will reflect the individual position of each code bar. The use of seven parallel code bars each shiftable to two positions will therefore provide 128 different output signal combinations, enabling that many indicia to be transmitted. Special design features are included in the transmitter of the invention to enable this large number of indicia to be transmitted without resorting to an excessive number of keys.

An additional feature of the transmitter of the invention is the use of a number of leaf spring switches which are positioned beneath the keys and are actuated by the depression of the keys. Each leaf spring switch is used in conjunction with a special function key of the transmitter. For example, certain shift keys when depressed actuate a leaf spring switch to vary the output signal which corresponds to the position of one or more of the code bars. Normally, one shift key is included in a transmitter of the type here described. However, we provide as an improvement in our invention three such shift keys, and this enables us to transmit a great number of symbols or characters as a coded signal. Each shift key actuates a separate leaf spring switch and each leaf spring switch is electrically connected to the switching means at the end of a code bar. The actuation of a leaf spring switch causes a reversal in the output signal from the circuit board to which the spring switch is operatively connected, and thus the corresponding code bar is effectively repositioned without mechanical movement since the output signal corresponding to that code bar position is reversed. Thus, the need for an additional key is eliminated. By providing three shift keys which function to vary the output signal in various combinations at three code bars, a great number of keys can be eliminated which would otherwise be required to transmit the large number of indicia.

Additional leaf spring switches are employed for other special functions. For example, a bail which extends across the width of the transmitter and which is moved by depression of a key contacts a leaf switch when it is depressed. This leaf switch is connected in the main electrical circuit of the transmitter such that it closes the circuit when actuated, that is, when the bail is depressed. With proper circuitry connections the output signal of the printed board is prevented from being transmitted until the bail and thus the leaf spring switch are actuated. Since the leaf spring switch is not actuated by a key until the key is substantially depressed, the complete shifting of the code bars prior to the transmission of the signal through this leaf spring switch is ensured. Thus a premature output code signal deliverable by the slight touch of the key is prevented.

Still another set of leaf spring switches is employed for what will be hereinafter termed a parity check system. The system operates in conjunction with an additional code bar and a main parity switch preferably of the type employed for the other code bars to provide an even or odd number of bits in the output signal. Since the output coded signal may be transmitted to a computer, an even or odd number of bits (whichever the computer is preset to accept) must be provided so that the computer will not reject the signal. The parity check system provides some ensurance that the computer receives an acceptable signal. The leaf spring switches of the parity check system are actuated to vary the output signal of the parity system when a variance is required. Such a variance is usually required because of a change in the output signal due to the depression of one or more shift keys. When this occurs the parity check system must be adjusted to compensate for the effective repositioning of the code bar which is achieved when the shift keys are employed.

Another feature of the invention is the use of a mechanism which is designed to multiply the motion of the spacer bar positioned at the lowermost portion of the keyboard. Because of proper positioning on the keyboard, most keys provide good leverage for the operator and require no mechanical amplification when depressed. However, since the spacer bar is positioned in a disadvantageous location on the keyboard relative to the internal mechanical components which are used to transmit motion, means are included to multiply the motion occurring when this bar is depressed. The spacer bar is linked with the internal mechanism by two spacer levers which extend out from each end of the bar. The multiplication means includes a linkage arm pivotally connected to a spacer key lever, and means to contact the linkage arm with a spacer lever when the spacer bar is depressed. This means is preferably a tab extending from and integrally secured to the spacer lever. In the preferred embodiment, the tab is positioned above the linkage arm and contacts it upon the depression of the spacer bar. As a result of this contact the motion of the spacer bar is transmitted through the pivoted joint to the spacer key lever. Thus a relatively slight touch of the spacer bar will be multiplied in its transmission to the spacer key lever.

To the accomplishment of the above and to such other objects as will hereinafter appear, the present invention relates to the construction of a telegraph keyboard transmitter as defined in the appended claims, and as described in the specification, taken together with the accompanying drawings in which:

FIG. 1 is a top plan view, partially in cross section, of part of a telegraph keyboard transmitter typical of the invention;

FIG. 2 is a side elevational view taken'alongstepped line 2--2 of FIG. I;

FIG. 3 is a bottom plan view of a circuit board included in the switching means employed in the transmitter of FIG. 1;

FIG. 4 is an edge view of the printed board shown in FIG. 3;

FIG. 5 is a fragmentary view partially in section, taken along line 5-5 of FIG. 2, of the switching means employed in the transmitter of the invention;

FIG. 6 is a fragmentary view taken along line 6-6 in FIG. 2, of a bail and leaf spring switch; and

FIG. 7 is a schematic illustration of the keyboard transmitter which is illustrated in FIG. 1.

Referring to FIG. 1, the keyboard transmitter includes an array of keys 10 only a few of which are illustrated. FIG. 7 shows a complete array of keys typically found in the transmitter. A spacer bar 12 is connectedto spacer levers 14, 16 which are pivotally supported by support means and 17 respectively. Each of the keys has an extended key lever. The four extreme left-hand levers (as viewed in FIG. 1) are designated 18, and the four extreme right-hand levers are designated 20. The key levers are secured at the rear end of the transmitter in the frame 22 and are guided in slots such as at 24. Automatic return of the key after depression is ensured by the applied pressure of the spring fingers 26 (best shown in FIG. 2). For convenience, the term key" is used herein to designate both the finger tab and the lever connected thereto.

A plurality of code bars 28, 30, 32, 34, 36, 38 and 40 are positioned substantially parallel to each other, and extend across the transmitter below the key levers l8 and 20. The bars are partly supported in slot frames 42 and 44 and terminate at one end below printed board 46. A bail 48 is pivotally supported by support members 50 and 52, linkage arms 54 and 56, and spring means 58. A leaf spring switch 60 is shown positioned at the end of the bail48 and below printed board 46. Additional leaf spring switches 62 and 64 are shown positioned beneath the key levers and still another leaf spring switch 66 is shown positioned beneath key levers 18. A typical construction for such leaf spring switches is illustrated in FIG. 6 and will be more fully described hereinafter. Switch 66 is actuated by the depression of key tab 69 which is shown to be connected to key lever 70. Leaf spring switch 60 is actuated by bail bar 48 while switches 62 and 64 are actuated by key tabs 71 and 73 respectively. Still other leaf spring switches may be included in the transmitter, but are not illustrated in FIG. 1.

The code bars 28-40 are notched code bars which are fully described in US. Pat. No. 2,977,413. As there indicated the bars are shifted to one of two positions by the depression of a key since the key lever engages the angled notches when depressed. Because the bars extend across substantially all of the keys, the depression of most keys will shift all code bars. With the proper positioning of notches in the various code bars, the depression of a key will cause each bar to assume a specific position and the resultant coded output signal is therefore an indication of the indicia represented by that key. Thus, if the number 7 is placed on a key tab and it is desired to select the number 7" for printing, the key tab is depressed by the operator, and the key lever arm engages the code bars in the proper notches to position each code bar separately to one of two positions. The code bars are shifted laterally, i.e., as viewed in FIG. 1 from left to right or from right to left. The notched construction referred to is illustrated in FIG. 5, wherein the code bar 40 is provided with notches 72, 74. The direction of travel of the code bar in FIG. 5 is indicated by the arrow 75 above the notches.

This shifting of the code bars is employed in the present invention to electrically transmit the proper coded signal for each key depressed. If there are seven code bars, a seven level code signal is transmitted on seven parallel output wires. In order to ensure that the shifted position of the code bars is accurately transmitted in the form of an electrical coded signal, there is provided a switching means which comprises the printed board 46 best shown in FIGS. 3 and 4, and a contact means which is best illustrated in FIG. 5. Referring to FIGS. 3 and 4 the'printed board 46 includes a plurality of conductive areas such as those designated by the numeral 76 which are preferably etched on the insulated base 47. The conductive areas 76 are positioned to form three, substantially parallel columns 78, 80 and 82. Each conductive area is connected to a terminal 84 by means of a conductive strip 86. As shown in FIG. 4, the terminals 84 are secured to the base 47 and electrically tied to the strip 86 by means such as rivet 88. The height of the riveted ends is less than the height of contacts 98 (FIG. 5), so that switching is performed without mechanical interference. External wires may readily be connected to the terminals 84 .to carry the input and output signals to and from the board.

For the purpose of understanding the operation of the switching means, two electrically conductive contact arms 90, 92 are shown in different positions on the board 46 in FIG. 3. These arms are connected to difierent code bars, e.g., the code bars 40 and 38 respectively. Arm 90 connects a conductive area 91 in column 82 with a conductive area 93 in column in the position shown in solid lines. However, the arm is repositioned (shown by dotted lines) when the code bar 40 to which it is attached is repositioned. In the new position the arm connects the same conductive area 91 in column 82 with a conductive area 95 in column 78. Contact arm 92 in its solid line position connects a conductive area 94 in column 82 with conductive area 96 in column 78, and is repositioned (shown by dotted lines) when the code bar 38 to which it is attached is repositioned, thereby to connect conductive area 97 in column 80 with conductive area 94. Thus if the conductive areas in column 78 were all connected to a power supply and those in column 80 were not so connected, the output signal taken from the conductive areas in column 82 by means of terminals 84 would alternately include the power supply voltage or not include it depending upon the position of the contact arms. With the contact arms positioned as shown in FIG. 3, the output signal corresponding to conductive area 91 would not include a voltage while that corresponding to conductive area 94 would include a voltage. In another embodiment, the power supply may be brought to the conductive areas in column 82 by a common lead wire. The output signal is then taken at the terminals connected to the conductive areas in columns 78 and 80 to which the voltage would be connected or not depending upon the positions of the contact arms as above described.

Other contact arms will be similarly connected across all levels of conductive areas (there are a total of eight levels shown in FIG. 3) in the same manner as arms 90 and 92 to provide an output coded signal which is directly dependent upon the positions of the code bars 28-36 to which they are respectively attached.

The movement of the contact arms in conjunction with the movement of the code bars may best be explained by referring to FIG. 5. As there shown the printed board 46 is positioned with conductive areas 91 and 93 placed above a contact arm 90 and in engagement with raised contact points 98, 99 on the contact arm. The contact arm 90 is held in engagement with the printed board by means of a spring means 100, which continuously urges it into slidable contact with the board. Both the contact arm 90 and the spring means 100 are secured in a recess 102 which is formed in the member 104. A part 106 depending from the member 104 is secured in the notch 108 on code bar 40. With this construction, when the code bar moves in either direction shown by the arrow 75, member 104 is caused to move with the code bar by virtue of its connection therewith, through the part 106. As a result, the contact arm 90 slides beneath the circuit board 46, and connects the several conductive areas 91 and 93 or 95 as described with reference to FIG. 3.

The electrical operation of the system can best be explained by referring to FIG. 7, wherein the code bars 28 to 40 are shown in relatively the same position as they are illustrated in FIG. 1, and the end of each code bar is schematically illustrated as being joined to a switching means. The switching means 100, 112, 114, 116, 118, 120 122 are equivalents of switching means described with reference to FIG. 5. Thus code bar 28 is joined to switch 1 10, code bar 30 to switch 112, code bar 32 to switch 1 14, code bar 34 to switch 116, code bar 36 to switch 118, code bar 38 to switch 120, and code bar 40 to switch 122. A common lead 124 is connected to a power supply (not shown) such as through terminal AA and bail switch S1, and is directly connected to contact arms 115, 117, 119 and 121 on switches 116, 118, 120 and 122 respectively. The common lead 124 is indirectly connected to the switches 110, 112 and 114 through leaf spring switches as will hereinafter be more fully explained. Each contact arm on switches 110 to 122 is the schematic equivalent of contact arm 90 in FIGS. 4 and 5. In addition, each switch is provided with contact points (such as points 126 and 128 on switch 122) which are schematic equivalents of the conductive areas on the circuit board 46 in FIG. 3.

Referring to switch 122, the contact arm 121 is connected to contact point 126 when code bar 40 is in one position, and is shifted to contact point 128 when the code bar is in a second position. This corresponds to the movement before explained with reference to FIG. 3. Terminal D represents the output terminal of the switch 122, and this terminal receives a voltage from contact point 126 when contact arm 121 is connected thereto, but does not receive a voltage from the non-energized contact point 128. Therefore, the output terminal D is either connected to the common lead 124 or to the non-energized contact point, depending upon the position of the code bar 40. This switch will therefore provide an output signal having a voltage or having no voltage in response to the movement of the code bar. The same type of output signal will be obtained from terminals E, F and G on switches 120, 118 and 116 respectively in response to the movement of their respective code bars.

Switches 110, 112 and 1 14 are not directly connected to the common lead 124, but are indirectly connected thereto through switches S3, S6 and S5 respectively. Each of the latter switches are leaf spring switches which are actuated by the depression of certain keys. For example, switch S3 is actuated by the depression of the shift key 136 and switch S6 is actuated by the depression of shift key 134, while switch S5 is similarly actuated by the depression of shift key 68. The switches S3 and S5 and S6 are arranged as shown in FIG. 7 to connect the common lead 124 to the contact points on the switches 110 through 114. Taking switch 110 as an example, it can be seen that contact arm 130 is directly connected to contact point 131 and may be shifted upon the movement of code bar 28 to contact point 132. The output terminal Q of this switch is directly connected to the contact arm 130. Since terminals O and P are directly connected to contact points 131 and 132 respectively the output signal will therefore be the signal present at the terminals 0 or P on this switch. It will be noted that terminal P is indicated as being directly connected to contact point $3 on switch S3, and terminal 0 is indicated as being directly connected to contact point S3, on switch S3. As shown, output terminal Q will have a voltage signal with the switches in the positions illustrated since it is connected to common lead 124 through switch S3. This can be clearly determined by tracing the path of connections of the various switches and terminals. For example, terminal 0 is directly connected to terminal 0 through contact arm 130. Terminal 0 is also connected to contact point S3, which is connected to contact point 54, on switch S4 through contact arm 83:. Contact point 84, is directly connected to terminal B which is illustrated as being connected to the common lead 124 through terminal B and to the voltage power supply through switch S1. Thus with the positions of the switches shown, an output voltage or a l is obtained at terminal Q, and if code bar 28 is shifted so as to connect contact arm 130 with contact point 132, then the output signal at terminal Q will be devoid of any voltage. Thus switches 110, 112 and 114 also function to provide an output coded signal having a l or 0 value depending upon the positions of their respective code bars.

As before indicated the output coded signal corresponding to a position of any of the code bars can be altered without changing the position of the code bar by depressing a shift key. FIG. 7 illustrates that the shift keys 68, 134 and 136 operate in conjunction with switches 110, 112 and 114, through the leaf spring switches S3, S5 and S6. Again taking switch as an example to indicate the operation of the switches in conjunction with the depression of shift key 136, it can be seen that the common lead 124 is shifted from contact point 131 to contact point 132, or vice versa, depending upon the position of contact arm 53, on switch S3. It will be noted that the common lead 124 is connected directly to the contact arm S3 through terminal B on the terminal board, as before mentioned. Thus the common lead 124 is alternately connected to either contact point 53;, or contact point S3, depending upon the position of the shift key 136. In turn, this common lead 124 is connected either to terminals 0 or P at switch 110. Thus, the output of switch 110 which appears at terminal 0 can be altered 'without shifting contact arm by simply switching S3 so that contact point 131 no longer carries a voltage from common lead 124.

The same variation in output signal may occur at any of the three switches 110, 112 and 114, depending upon which of the shift keys is depressed. An analysis of the other switches and their connections to switches 112 and 114 will indicate that the same electrical variation is effected when shift keys 68 and 134 are depressed. Therefore a variety of signals can be obtained from these three levels of output signal by actuation of the shift keys in various combinations. When the output signal from the other four levels are included, it will be appreciated that a large number of output coded signals may be transmitted. It will be necessary to place several indicia on each of the key tabs and also to sometimes depress several keys at one time in order to accomplish the variety of signals which can be obtained. The important advantage, however, which is achieved when three shift keys are employed is a development which is important to the overall objectives of a transmission system of this type.

FIG. 7 illustrates a plurality of switches which are employed for the parity check system. The main parity switch is shown at $10, and it is illustrated as being connected to an eighth code bar 158. This code bar is positioned and structured similarly to the other seven code bars so that when a key is depressed, the key lever also engages the notches on the code 158 and shifts it to one of two positions. The switch S10 is similar to switches 110 to 122 as they are illustrated in FIG. 5. Common lead 124 is connected through the various switches S7, S8 and S9 to the terminals on the switch S10. These switches are leaf spring switches which are actuated by the depression of shift keys and function to reverse the connection of the common lead to either contact point 160 or 162 on $10. The reversal of the common lead position occurs when necessary to indicate a proper output signal from contact arm 164. The output signal from contact arm 164 will of course be either a voltage i.e., from common lead 124, or no voltage. Thus, the output of the parity switch will include a 1 or a, depending upon the position of code bar 158. This output signal is used to supplement the output signal from the other code bars. The overall purpose of such a supplementary action is to provide a total signal for a computer or equivalent mechanism which includes an even number of ls" or bits. The computer is generally adapted to receive a signal which includes only an even number of bits (or in some instances which includes only an odd number of bits). Thus, if the output coded signal from the seven code bars includes an odd number of bits due to the depression of a particular key, the parity check system will be adjusted by the eighth code bar to provide another bit. The result is that the eight level signal which is transmitted to the computer now includes an even number of bits, and the signal will not be rejected by the computer. Switches S7, S8 and 89 function to reverse the signal whenever necessary at the main parity switch S10 in order that the output of the parity switch is adjusted to include any reversals in the output signal due to shifting or the like. These switches are also leaf spring switches which are actuated by the depression of the shift keys. For example, switch S9 is actuated when shift key 134 (switch S6) is depressed, switch S8 is actuated when key 68 (switch S) is depressed and'switch S7 is actuated when key 136 (switch S3) is depressed. In this manner, the output of the main parity switch S10 includes any variations due to shifting.

Since the output signal of the printed board depends upon the movement of the contact arms it is important that this movement be synchronized with the full depression of a key so that a premature output signal is avoided. In order to ensure synchronization we provide a mechanism which is most clearly shown in FIGS. 1, 2 and 6. Referring to FIG. 1, the bail 48 is shown as extending beneath the printed board 46 and above a leaf spring switch 60. In FIG. 2 the leaf spring switch 60 is shown to be actuated by the pressure applied from the bail 48 which in turn is moved by the key lever 138. This leaf spring switch 60, which is depicted most clearly in FIG. 6, consists of separated contact points 140 and 142 and a contact arm 146 located between them and carrying a member 144 which normally extends to a position just below the bail 48. The contact arm 146 is biased to connect with contact point 140 and is repositioned to connect with contact point 142 when the bail 48 is moved into contact with the member 144. This occurs, as before mentioned, when a key is depressed and the corresponding key lever such as 138 transmits the motion to the bail bar. The member 144 is positioned such that the key tab is substantially fully depressed before the bail 48 depresses member 144 causing contacts 146 and 142 to close. A spring means 58 best shown in FIG. 2 returns the bail to its normal position after the key is released and as a result the switch shown in FIG. 6 resumes its normal position. The operation is again repeated upon the depression of the next key. The leaf spring switch 60 is schematically illustrated in FIG. 7 as a single-pole single-throw switch S1. As above explained this switch may be connected to the common lead 124 at one end and to the voltage supply at the other end as shown, or to time delay electronic equipment (not shown). In either case the switch functions to intercept the signal which is being transmitted so that it does not pass through the printed board to the output equipment until the code bars and thus the contact arms are fully shifted. In the illustration of FIG. 7 this is achieved by maintaining switch S1 in an open position until the key operating this switch is substantially depressed, at which time the switch closes and the supply voltage (at terminal AA) is connected to common lead 124.

- As indicated above, the transmitter of the invention includes a mechanism which is designed to multiply the motion of the spacer bar 12. This mechanism is best illustrated in FIGS. 1 and 2. Referring to FIG. 1, the spacer lever 14 has a tab 148 secured thereto and extending laterally therefrom to a point above linkage arm 152, the latter being connected to spacer key lever 154, by means of an extended tab 156 which overlies lever 154. FIG. 2 illustrates these components from a side view (shown in dotted outline). In operation the spacer bar 12 isdepressed and the spacer lever 14 is therefore also depressed. As a result the tab 148 contacts linkage arm 152 to cause it to move in a downward direction with the result that tab 156 transmits the motion to key lever 154. The combination of motions described causes a multiplication of the initial movement and facilitates the required manipulation by the operator.

Additional special functions may be included in the transmitter as indicated by key 166 in FIG. 7 which functions to provide a repeat function. That is, when key 166 is depressed, it actuates switch S4 which may preferably be a leaf spring switch, and the output coded signal is thereby routed through terminal R to associated electronic equipment (not shown) to cause the previous output signal to be repeated. Any number of other special functions, such as those which are normally employed in a keyboard transmitter of the type described can also be included with the proper auxiliary equipment.

It is believed that the construction and operation of our improved keyboard transmitter will be apparent from the foregoing detailed description. The keyboard is characterized by its simplicity and low cost. It may be compactly packaged and used as a portable unit for local transmission such as by means of telephone equipment or the like or may be connected directly to a computer for information storage.

The switching in the transmitter usually occurs at very low voltages and currents, thereby tending to avoid the generation of noise radiated from the keyboard which may harm other transmissions being sent locally, or which in military use may reveal the location of the transmitter. Currents in the order of 10 milliamps and voltages between about 5 and 20 volts are normally used.

- While the particular embodiment described is directed to the use of output signals comprising a voltage or no voltage i.e., a l or 0, modifications may be made to provide polar switching. By polar switching is here meant that the output of the printed circuit board for each signal level is a positive power signal at one switch position of the code bar and a negative power signal at the other position. With this arrangement,

the direction of the output signal current is reversed for a l condition and a 0 condition. Such an arrangement is readily accomplished by using a printed circuit board design in which connections are made to each conductive area on the board and brought out separately from the board.

In the foregoing description it has been assumed that there are seven code bars which operate to provide a seven level coded output signal. However, any number of code bars can be included with the proper adjustments in the transmitter equipment.

No power supply is shown in the drawings for the signal lines, the signal power being put on the common lead by the circuitry of the transmitter in which the keyboard is used, or from an external piece of equipment.

Mechanical features of the keyboard not described in detail may be assumed to be shown in the above referred to US. Pat. No. 2,977,413. Thus the code bars may have special locks slots for repeat key and may have other lock slots for a lock lever to hold the code bars even if the key rises before the entire character has been transmitted.

It will be apparent that while we have shown and described the improvement in a preferred form, many changes may be made therein without departing from the spirit and scope of the invention.

We claim:

1. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of connective areasv mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, said contact means comprising a member having a depending part, means to operatively connect said depending part to a code bar, and an electrically conductive contact arm secured to said member, said contact arm being positioned engageable with said base to connect said conductive areas.

2. The transmitter of claim 1, in which n substantially parallel code bars are provided, n being an integer greater than 1, each of said code bars being connected to a contact means to thereby obtain an n level output coded signal.

3. The transmitter of claim 2, in which there is provided an additional code bar shiftable to one of two positions by the depression of a particular key, and in which there is provided a main parity switch separately actuated by movement of said additional code bar, whereupon when said particular key is depressed said additional code bar is shifted to actuate said main parity switch to thereby provide a parity check of the shifted positions of the other code bars.

4. In the transmitter of claim 1, a spacer bar, and means for multiplying the motion of said spacer bar, said means comprising a linkage arm, a spacer key lever pivotally secured to said linkage arm, and means for connecting said spacer bar and said linkage arm when said spacer bar is depressed to thereby transmit motion of said bar to said spacer key lever.

5. In the transmitter of claim 4, at least three shift keys, each of said keys having a switch means operatively connected thereto and actuated by the movement thereof, each of said switch means being electrically connected to a different one of said contact means and effective when actuated to alter the output coded signal of its corresponding contact means without further shifting of said contact means.

6. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, each of said contact means comprising a slidable member having a depending part and also having a recess, means to secure said depending part to a code bar, an electrically conductive contact arm secured in said recess, and a spring means positioned in said recess so as to urge said contact arm into engagement with said conductive areas on said base whereupon when said code bar is shifted said contact arm is also shifted to connect different conductive areas on said base.

7. In the transmitter of claim 6, at least one shift key, and a second switching means operatively connected to said shift key so as to be actuated thereby, and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said circuit board corresponding to the position of said code bar is altered.

8. In the transmitter of claim 6, a bail operatively connected to a key so as to be moved thereby, second switching means, means operatively connected between said bail and said second switching means for actuating the latter when the former is moved, means electrically connecting said second switch to said base and effective to prevent an output coded signal from said base until said second switching means is actuated, said bail being actuated by said key after a substantial movement of said key, whereupon the output coded signal from said base is prevented until said code bars are fully shifted by the substantial movement of the key.

9. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, a bail operatively connected to a key so as to be moved thereby, second switching means, means operatively connected between said bail and said second switching means for a actuating the latter when the former is moved, means electrically connecting said second switch to said base and effective to prevent an output coded signal from said base until said second switching means is actuated, said bail being actuated by said key after a substantial movement of said key, whereupon the output coded signal from said base is prevented until said code bars are fully shifted by the substantial movement of the key.

10. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base forvone position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, at least one shift key, and a second electrical switching means operatively connected to said shift key so as to be actuated thereby and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said base corresponding to the position of said code bar is altered, a third switching means, a parity switch, said third switching means being also operatively connected to and actuated by said shift key, said third switching means being electrically connected to said parity switch to adjust the effective position of said parity switch when the output signal of a code bar is altered by the movement of said shift key.

1 l. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shift thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, a spacer bar and means for multiplying the motion of said spacer bar, said means comprising a linkage arm, a spacer key lever pivotally secured to said linkage arm, and means for connecting said spacer bar and said linkage arm when said spacer bar is depressed to thereby transmit motion of said bar to said spacer key lever.

12. The transmitter of claim 11, in which said means for connecting said spacer bar and said linkage arm comprises a tab operatively connected to said spacer bar, said linkage arm being positioned below said tab, whereupon when said spacer bar is depressed said tab contacts said linkage arm to thereby transmit the motion of said bar to said key lever.

13. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, at least one shift key, and a second electrical switching means operatively connected to said shift key so as to be actuated thereby and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said base corresponding to the position of said code bar is altered.

14. A keyboard operated telegraph transmitter comprising an array of keys, a plurality of said keys being shift keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, circuit means, means to transmit the movement of said code bars into an output coded signal from said circuit means, and electrical switching means electrically connected to said circuit means, said switching means being operatively connected to said shift keys and being actuated by the'actuation of said shifi keys, whereupon when a shift key is actuated the output coded signal of said circuit means is altered to thereby provide a variety of output signals for a single position of said code bars.

15. The transmitter of claim 14, in which there are n substantially parallel code bars, where n is an integer greater than 1, and each of said shift keys when actuated alters the output coded signal corresponding to one of said code bars.

* it i 

1. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of connective areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, said contact means comprising a member having a depending part, means to operatively connect said depending part to a code bar, and an electrically conductive contact arm secured to said member, said contact arm being positioned engageable with said base to connect said conductive areas.
 2. The transmitter of claim 1, in which n substantially parallel code bars are provided, n being an integer greater than 1, each of said code bars being connected to a contact means to thereby obtain an n level output coded signal.
 3. The transmitter of claim 2, in which there is provided an additional code bar shiftable to one of two positions by the depression of a particular key, and in which there is provided a main parity switch separately actuated by movement of said additional code bar, whereupon when said particular key is depressed said additional code bar is shifted to actuate said main parity switch to thereby provide a parity check of the shifted positions of the other code bars.
 4. In the transmitter of claim 1, a spacer bar, and means for multiplying the motion of said spacer bar, said means comprising a linkage arm, a spacer key lever pivotally secured to said linkage arm, and means for connecting said spacer bar and said linkage arm when said spacer bar is depressed to thereby transmit motion of said bar to said spacer key lever.
 5. In the transmitter of claim 4, at least three shift keys, each of said keys having a switch means operatively connected thereto and actuated by the movement thereof, each of said switch means being electrically connected to a different one of said contact means and effective when actuated to alter the output coded signal of its corresponding contact means without further shifting of said contact means.
 6. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said codE bars for the key which is selected, each of said contact means comprising a slidable member having a depending part and also having a recess, means to secure said depending part to a code bar, an electrically conductive contact arm secured in said recess, and a spring means positioned in said recess so as to urge said contact arm into engagement with said conductive areas on said base whereupon when said code bar is shifted said contact arm is also shifted to connect different conductive areas on said base.
 7. In the transmitter of claim 6, at least one shift key, and a second switching means operatively connected to said shift key so as to be actuated thereby, and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said circuit board corresponding to the position of said code bar is altered.
 8. In the transmitter of claim 6, a bail operatively connected to a key so as to be moved thereby, second switching means, means operatively connected between said bail and said second switching means for actuating the latter when the former is moved, means electrically connecting said second switch to said base and effective to prevent an output coded signal from said base until said second switching means is actuated, said bail being actuated by said key after a substantial movement of said key, whereupon the output coded signal from said base is prevented until said code bars are fully shifted by the substantial movement of the key.
 9. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, a bail operatively connected to a key so as to be moved thereby, second switching means, means operatively connected between said bail and said second switching means for a actuating the latter when the former is moved, means electrically connecting said second switch to said base and effective to prevent an output coded signal from said base until said second switching means is actuated, said bail being actuated by said key after a substantial movement of said key, whereupon the output coded signal from said base is prevented until said code bars are fully shifted by the substantial movement of the key.
 10. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said Code bars for the key which is selected, at least one shift key, and a second electrical switching means operatively connected to said shift key so as to be actuated thereby and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said base corresponding to the position of said code bar is altered, a third switching means, a parity switch, said third switching means being also operatively connected to and actuated by said shift key, said third switching means being electrically connected to said parity switch to adjust the effective position of said parity switch when the output signal of a code bar is altered by the movement of said shift key.
 11. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shift thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, a spacer bar and means for multiplying the motion of said spacer bar, said means comprising a linkage arm, a spacer key lever pivotally secured to said linkage arm, and means for connecting said spacer bar and said linkage arm when said spacer bar is depressed to thereby transmit motion of said bar to said spacer key lever.
 12. The transmitter of claim 11, in which said means for connecting said spacer bar and said linkage arm comprises a tab operatively connected to said spacer bar, said linkage arm being positioned below said tab, whereupon when said spacer bar is depressed said tab contacts said linkage arm to thereby transmit the motion of said bar to said key lever.
 13. A keyboard operated transmitter comprising an array of keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, each of said code bars being shifted thereby to a predetermined position corresponding to the particular key which is actuated, switching means operatively connected to said code bars and actuated by the shifting thereof, said switching means comprising a base having a plurality of conductive areas mounted thereon, and contact means operatively connected to each of said code bars and selectively engaging said conductive areas, said contact means connecting certain of said conductive areas on said base for one position of the code bars and other conductive areas for another position of said code bars, thereby to provide a coded electrical output signal from said base which corresponds to the shifted positions of the said code bars for the key which is selected, at least one shift key, and a second electrical switching means operatively connected to said shift key so as to be actuated thereby and electrically connected to one of said contact means, whereupon when said shift key is moved and said second switching means is actuated, the output signal of said base corresponding to the position of said code bar is altered.
 14. A keyboard operated telegraph transmitter comprising an array of keys, a plurality of said keys being shift keys, a plurality of code bars operatively connected to said keys, means for shifting said code bars when a key is actuated, circuit means, means to transmit the movement of said code bars into an output coded signal from said circuit means, and electrical switching means electrically connected to said circuit means, said switching means being operatively connected to said shift keys and being actuated by the actuation of said shift keys, whereupon when a shift key is actuated the output coded signal of said circuit means is altered to thereby provide a variety of output signals for a single position of said code bars.
 15. The transmitter of claim 14, in which there are n substantially parallel code bars, where n is an integer greater than 1, and each of said shift keys when actuated alters the output coded signal corresponding to one of said code bars. 